Robotic evaluation of articular laxity (REAL) classification: a new intraoperative knee soft-tissue laxity classification using ROSA robotic software

• DOI: 10.1007/s00590-025-04265-w
• Publication Date: 2025-03-31T14:35:34Z
• Authors: Eustathios Kenanidis; Nikolaos Milonakis; Alexandros Maslaris; Eleftherios Tsiridis

Abstract Purpose Currently, there is no widely accepted method for measuring soft-tissue laxity and defining a balanced total knee arthroplasty (TKA). We aim to evaluate whether robotic technology can facilitate the categorization of intraoperative laxity. Methods Our study was conducted in two phases. A senior surgeon performed imageless robotically assisted TKAs (ra-TKAs) using functional alignment. The first phase included 120 patients. Following surgical approach, medial lateral recorded extension 90° flexion. distribution difference sum laxities flexion assessed classify phenotypes. second validated classification 102 additional ra-TKAs. Laxity phenotypes were evaluated at start end procedure. Results followed normal distribution, facilitating into three groups, with standard deviation 2.5 mm. Three categories mediolateral severity established: < mm, 2.5-5 > 5 These groups coded as 1, 2, 3 A, B, C, respectively. Nine emerged from combination (1A-C, 2A-C, 3A-C). Phenotypes 1A 1B most common operation’ beginning, while 3B 1C rarest. At operation, 93% categorized class 1B, “balanced area”. Conclusion recognized nine phenotypes, potentially laying groundwork consensus on balancing.